— 191 — 



211°; d 20 o 0,942, n D20 o 1,4830. In order to convert it into A 3 -p-menthenol-8, 

 a solution of 20 g. tetrahydro-p-acetyltoluene in 60 cc. ether was poured 

 into a Grignard's solution prepared by heating 36 g. methyl iodide, 6 g. 

 magnesium and 110 g. ether. After heating for 2 hours on the water bath 

 the mass was diluted with water and subjected to steam distillation. This 

 process yielded pure zl 3 -p-menthenol-8, possessing the following properties: 

 m. p. 39°, b. p. 97° (14 mm), 205° (ord. press.), di 8 o 0,921, n D18 o 1,4769. 

 The preparation has the peculiarity of remaining for a long time in an 

 over-melted condition, resembling a-terpineol in this respect, as well as 

 in its odour. It forms a phenylurethane, which melts at 128° when slowly 

 heated. The zl 3 -p-menthenol-8 which was obtained from tetrahydro-p-toluic 

 acid by Perkin and Pickles has the same properties as that of Wallach: 

 m. p. 40 to 41°, b. p. 108 to 110° (30 mm.), m. p. of the phenylurethane 

 133 to 134° (without decomposition when rapidly heated). 



Wallach, by splitting-off water from zl 3 -p-menthenol-8 by means of 

 oxalic acid, obtained zl 3 ' 8(9 )-p-menthadiene (b. p. 184 to 185°; di 9 o 0,858; 

 n D i90 1,4924). The constitution of this body was placed beyond doubt by 

 oxidising with l°/o permanganate solution, when /3-methyladipic acid resulted, 

 the formation of which is readily explicable from the position of the double 

 bond in the ring. By heating zl 3 -p-menthenol-8 with magnesium methyl 

 iodide Perkin l ) has obtained a menthadiene of which the properties agree 

 with those of the zl 3 ' 8(9) -p-menthadiene referred to above (b. p. 184 to 

 188°; d 20 o 0,8600; n D20 o 1,4915), thus proving the identity of the two hydro- 

 carbons. The authors were not able to prepare derivatives from which the 

 body could be identified. The following table shows the properties of A 1 - 

 and J 3 -tetrahydro-p-acetyltoluene, zl 3 -p-menthenol-8, zl 3 ' 8 ^-p-menthadiene, 

 z^-p-menthenol-S («-terpineol), and zl ^^-menthadiene: — 



A 3 -Tetrahydro-p-acetyltoluene A ^Tetrahydro-p-acetyltoluene 



b. p 205 to 206° 210 to 211° 



d 0,940 0,942 



n D 1,4719 1,4830 



Mol. refr 41,10 41,84 



M. p. of the oxime . . 51° 116 to 117° 



M. p. of the semicarbazone 165° 222° 



zl 3 -p-Menthenol-8 A ^p-Menthenol-S («-Terpineol) 



M. p 39° 35° 



B. p 205° 218° 



d 0,921 0,938 



n 1,4764 1,4820 



M. p. of the phenylurethane 128° 113° 



J ) Comp. Journ. chem. Soc. 88 (1906), 848; Report October 1906, 107. 



